Yume de Mita Ano Ko no Tame ni

Senri Nakajou's twin brother was his everything, the one who protected him from their abusive father, the one whose pain he felt as his own. That is, until the day thirteen years ago when Senri's entire family was murdered before his eyes. He couldn't have cared less about his parents, but without his brother, his world ended. Ever since, finding the killer and making him pay has been Senri's only goal...and now-finally-he's caught a glimpse of a clue...!

(Source: Yen Press)